Horological instrument

ABSTRACT

A horological instrument includes an oscillator such as a balance wheel. The oscillator carries a coil, which may consist of a single conductive ring. Current is induced in the moving coil by mutual induction from a fixed coil. One or more fixed magnetic fields are positioned to drive the energized coil. A circuit is provided to energize the coil with current at the proper moment during its oscillation.

United States Patent Meitinger [4 1 June 6, 1972 HOROLOGICAL INSTRUIVIENT Primary Examiner-Stephen J. Tomsky Assistant Examiner-Edith C. Simmons Jackmon [72]- Inventor: Helnz Meltlnger, Pforzhelm, Germany Atmmey Richard A. Joel [73] Assignee: Timex Corporation, Waterbury, Conn.

[57] ABSTRACT [22] Filed: July 6, 1970 A horological Instrument includes an oscillator such as a PP 4 balance wheel. The oscillator carries a coil, which may consist of a single conductive ring. Current is induced in the moving coil by mutual induction from a fixed coil. One or more fixed d 8 23 23 28 R 8 magnetic fields are positioned to drive the energized coil. A l I o arc circuit is provided to energize the coil with current at the 310/36 proper moment during its oscillation. [56] References Cited 12 Claims, 5 Drawing Figures UNITED STATES PATENTS 1,801.958 4/1931 Haydon 3,186,157 6/1965 Favret et a1 ..58/28 I-IOROLOGICAL INSTRUMENT DESCRIPTION The present invention relates to horology and more particularly to a horological instrument utilizing an electronic circuit.

The improvement in battery construction and capability in recent years has provided renewed interest in horological instruments having a self-contained source of power. A clock may now be manufactured having a battery within its case, thereby avoiding the necessity of connecting the clock to an electrical outlet. Similarly, a watch may now be manufactured in which a small button type of primary battery cell is contained within the watch case and provides the power to operate the watch movement.

Various approaches have been taken by manufacturers of horological movements in applying the timekeeping ability of an oscillator to an electronic horological instrument. For example, watches have been manufactured in which one or more magnets have been mounted on a balance wheel, which carried the magnets through the fields of one or more coils. Such movements have either utilized a make-break contact carried by the balance wheel or a separate pick'up coil which triggers an electronic circuit. In another type of watch movement the balance wheel carries a coil which moves through the field of a number of permanent magnets which are fixed to the watch plate. The coil receives current either througha make-break contact or by means of two hairsprings. Various other systems have been proposed. However, generally they require that the oscillator, for example, the balance wheel or tuning fork, carry either a coil or a magnet.

sensitive to external magnetic influence or external demagnetizing forces. In those horological instruments in which the oscillator carries an electric coil, it is necessary that current reach the coil. The means by which the current is carried to the moving coil, for example, the use of two hairsprings or make-break contacts, may present difficulties in regard to the expense of the movement. It isnecessary to electrically isolate the coil, hairspringand contacts from other portions of the balance wheel and such electrical isolation may be accomplished using plastic materials. However, such plastic materials may be sensitive to humidity, so that their weight increases in a humid atmosphere, causing the balance wheel to become less perfectly balanced.

It is the objective of the present invention to provide a horological instrument utilizing an oscillator as its time base in which the oscillator is not sensitive to changes in humidity; in which the oscillator assembly is relatively simple and inexpensive; and in which the oscillator does not present difficulties in magnetic shielding.

' In accordance with the present invention, a horological instrument is provided in which the oscillator carries a coil. The coil may be a single blanked turn of copper or other conductive non-magnetic material; An electric current is induced into the coil carried by the oscillator by means of a coil fixed to the movement. The induced current in the moving coil reacts with a permanent magnet or a magnetic field of a second coil, the

, permanent magnet or second coil being fixed to the movement.

The oscillator, which may be a balance wheel, need be connected to the movement frame and bridge only by its pivoting and spring mechanisms, for example, in the case of a balance wheel, the balance wheel staff and its conventional hairspring.

be self-starting. The circuit is a self-oscillating circuit whose frequency is determined by the movement of the physical oscillator but which, in addition, has a self-oscillating frequency of its own for the purpose of starting the motion of the physical oscillator. The circuit is triggered or synchronized by the movement of the physical oscillator. It is possible, due to the arrangement of the coils, to provide that the indexing of the index wheel of the movement occurs from one of the coils fixed to the plate rather than from, as in other watches, the

moving oscillator. This enables the physical oscillator to be relatively free-moving and undamped.

Other objectives will be apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings. In the drawings:

FIG. 1 is a perspective view of a balance wheel oscillator and its associated driving mechanism;

FIG. 2 is a side view taken along line A-A of FIG. 1;

FIG. 3 is a circuit diagram of the electronic circuit utilized in connection with the present invention;

FIG. 4 is a diagram showing the wave forms in the circuit of FIG. 3; and v FIG. 5 illustrates the arrangement of the permanent magnet and lower shunt.

The present invention is described in connection with a watch movement. However, it is also applicable to other horological instruments, such as balance wheel stationary clocks, balance wheel automotive clocks and pendulum wall clocks, etc.

The watch mechanism of the present invention is shown in FIG. 1. A balance wheel 10 is mounted on a balance wheel staff 11. The balance wheel staff is connected, by means of a hub, to the inner end of theconventional type of horological hairspring 12. The outer end of the hairspring I2 is connected to the frame or bridge of the movement (not shown). The balance wheel comprises a cross-spoke member 13 through which the balance staff protrudes, a counter-balance portion 1 4 which is in the form of a partial rim and a coil 15 carried by the cross-spoke 13. The coil 15 may be constructed of many turns of fine wire which are held'by an adhesive and the coil joined to the cross-spoke 13 by an adhesive. The preferred embodiment, however, as shown in FIG. 1, is that'the coil 15 is a winding consisting of a single turn. The entire balance wheel, including the single turn winding 15, may be stamped (blanked) of a suitable non-magnetic conductive material, such as copper or phosphor bronze.

An induction coil 16 is fixed to the plate of the watch movement. The induction coil 16 has a center hole through which a U-shaped induction shunt 17 is positioned. The induction shunt 17 is of a soft magnetic permeable material such as iron. The arms of the induction shunt are formed to provide an air gap 18 through which the coil 15 moves. Drive coil 19 is also fixed to the plate of the movement. The drive coil 19 has a center hole within which a weak permanent magnet 20 is positioned. The permanent magnet 20 is physically connected to a lower shunt 22 of the drive coil 19. The lower shunt is preferably of such a shape that maximum magnetic induction arises at radial portions of coil 15. For purposes of illustration the lower shunt is shown in FIGS. 1 and 5 as being U" shaped. The lower shunt 22 is positioned beneath the path of movement of the moving coil 15. The upper shunt 21 of the driving coil is positioned, for example, by adhering it to a bridge member of the watch movement, above the path of movement of the coil 15. The upper shunt 21 like the lower shunt 22 is preferably of such a shape that maximum magnetic induction arises at radial portions of coil 15. For purposes of illustration the upper shunt is shown in FIG. I as being a half ring. Again, as in the case of the lower shunt shown in FIG. 1, the upper shunt is shown as only a half ring for the purpose of illustration.

The electronic circuit is illustrated in FIG. 3. The electronic circuit includes a battery 30 or other source of direct current. Preferably the battery 30 is positioned within the case of the movement. The positive terminal of battery 30 is connected to one terminal of coil 16. The positive terminal of battery 30 is also connected to the cathode of diode 31 and to the emitter 32 of the transistor 33. The collector 34 of transistor 33 is connected to the base 35 of transistor 36. The emitter 37 of transistor 36 is connected to the anode of diode 31 and to the anode of diode 38. The cathode of anode 38 is connected to the negative terminal of the battery 30. A resistor 39 is connected between the base of transistor 33 and the negative terminal of the battery, which may be ground. A capacitor 40 is connected between the base of transistor 33 and the base 41 of transistor 42. The emitter 43 of transistor 42 is connected to the cathode of diode 44, the anode of which is connected to the base 41. The emitter 43 is also connected to one terminal of the drive coil 19, to one side of the capacitor 45, and also to one terminal of the induction coil 16. The opposite terminal of the drive coil 19 is connected to one side of the capacitor 46. The other side of which is connected to the collector 47 of the transistor 36.

The operation of the device and circuit is shown in connection with the wave form diagram of FIG. 4. In FIG. 4 the X-ordinate (abscissa) is time and the Y-ordinate (ordinate) is current. The current I and current Ilrefers to the current in the drive coil 19 at different times; it is the driving impulse current. The current 16 is the current in the induction coil 16. The current is the current induced into the coil 15 carried by the balance wheel.

When the coil 15 moves within the airgap 18 fonned between upper shunt 21 and the lower shunt 22 a current (back e.m.f.) is induced in the coil 15 by the permanent magnet 20. That current in the coil 15 causes a magnetic field from the coil which causes a change of magnetic flux in the shunt 17. The change of flux in shunt 17 induces a current change across the induction coil 16. That change across the coil 16 acts to trigger the circuit to produce a driving impulse.

t Specifically, having regard to the circuit diagram of FIG. 3 a current change at the coil 16, by means of diode 44 and capacitor 40, triggers the transistor 33 to conduct. The battery current flows through transistor 33 and triggers transistor 36, causing current to flow through diode 38.

AS soon as transistor 36 starts to conduct a battery current change occurs in coil 19 by means of capacitor 46, transistor 36, and diode 38this current change being represented by current I in FIG. 4. When the current in coil 16 rises it induces a current in the coil 15 (short circuit winding) of the balance wheel. The current induced in the coil 15 cooperates with the magnetic field of the shunts 21 and 22 (of coil 19) to provide a driving impulse to the balance wheel.

During the driving impulse the transistor 43 is blocked by the voltage induced in coil 16. At that moment capacitor 45 is already charged via the diode 38. The capacitor 46 becomes saturated and the current through the coils l6 and 19 decreases. The magnetic flux from coil 19 decreases resulting in'a decreased voltage from coil 16. The control current from coil 16 to transistor 33 decreases lowering the control current to transistor 36. This results in decreasing the current through transistor 36 and the coils 16 and 19. The effect is regenerative, as again the induced voltage of coil 16 is reduced, until finally the transistor 36 is blocked (non-conductive). The current through coil 16 falls rapidly, the rate of fall being limited only by the inductance of thecoil. The fall of current in coil 16 charges capacitor 45 to above the battery voltage. The charge on capacitor 45 enables coil 19'to conduct during the impulse of the next oscillation. The change in current in coil 16 induces an inverted current in the coil 15 carried by the balance Wheel.

The transistor 42 becomes conductive by the charging current of capacitor 40, which flows from the battery 30 by way of resistor 39. The capacitor 46 is discharged by way of transistor 42 and coil 19. The current in the coil 19 at this time, designated current II in FIG. 3, is inverse to the direction of battery current. The coil 19, with the flow of current II, induces a magnetic flux of inverted direction, relative to the flux of current I. That inverted flux cooperates with the induced inverted current of coil 15 to provide a drive impulse to the balance wheel in the same direction as the first driving impulse. The driving impulses are only provided for one direction of motion of the balance wheel.

The circuit of FIG. 3 operates as a resistor-capacitor self oscillating multivibrator when the balance wheel is stopped. The frequency is detemiined by capacitor 40 and resistor 39. That frequency furnishes induced current impulses to the balance wheel coil 15 for the self-starting of the watch.

The indexing may be from the balance wheel or from the coils. For example, a hub (plateau) fixed to the balance wheel staff may carry a pin which index a fork, the fork indexing an index wheel. Alternatively the coil 16 or the coil 19 may be the coil for a moving armature which indexes an index wheel. This alternative has the advantage that the balance wheel will not be damped by the indexing of the index wheel.

It should be noted that the circuit of FIG. 3 may be synchronized by an external circuit. For example a synchronizing signal may be provided by a quartz crystal oscillator circuit whose high frequency is counted down by divider circuits.

I claim:

1. In a horological instrument having a frame, an oscillator system including an oscillator mounted on said frame so that it may be oscillated, said oscillator carrying an electrically conductive moving coil, means mounted on said frame to create a magnetic field through which the moving coil passes so that a voltage is induced in said moving coil, a first and a second fixed coil mounted on said frame, a first magnetic shunt positioned next to said first coil so that changes of flux in said first shunt result in an electrical change in said first fixed coil, said first shunt also being positioned near to the path of movement of said moving coil, so that the moving coil induces flux changes in said first shunt, a source of electric current, an electric circuit having an input and an output and connected to said source, the said input being connected to said first fixed coil and responsive to electrical changes in said first fixed coil to then produce a pulse at its output, said second fixed coil being connected to said output so-that upon being impulsed it creates a second magnetic field in the path of the moving coil and thereby drives said moving coil.

2. An oscillatory system as in claim 1 wherein said means to create a magnetic field is a permanent magnet.

3. An oscillatory system as in claim 1 wherein said moving coil is a single turn of conductive material.

4. An oscillatory system as in claim 3 wherein said oscillator is a balance wheel which carries the single turn coil.

5. An oscillatory system as in claim 1 wherein said first shunt is a Ushaped member the ends of whose arms form an air gap through which the moving coil moves. 7

6. An oscillatory system as in claim 5 wherein the first fixed coil has a hole within which is positioned the shank of the first shunt.

7. An oscillatory system as in claim 1 wherein said second coil is positioned near to a second magnetic shunt and said second magnetic shunt is positioned near the path of movement of said moving coil, to concentrate the magnetic field from said second coil.

8. A horological instrument including an oscillator, a short circuit moving electric coil carried by said oscillator, a fixed coil positioned near the path of movement of said moving coil and adapted to induce current into the moving coil, pick-up means to detect the position of said moving coil, a current source, a circuit connected to said current source and controlled by said pick-up means, said circuit being connected to said fixed coil to provide drive pulses to said coil thereby impulsing said oscillator, and means to create a magnetic field within which the moving coil moves.

9. A horological instrument as in claim 8 wherein said cir cuit is self-oscillating for self-starting of the oscillator.

10. A horological instrument as in claim 8 wherein said circuit includes a multivibrator.

11. A horological instrument as in claim 8 wherein said oscillator is a balance wheel and said coil is a single short-circuit turn.

1-2. A horological instrument as in claim 8 wherein said pick-up means includes a magnetic shunt having an air gap through which the coil moves and a coil connected to the circuit and proximate to the shunt and wherein a permanent magnet is positioned next to the path of movement of said 5 moving coil. 

1. In a horological instrument having a frame, an oscillator system including an oscillator mounted on said frame so that it may be oscillated, said oscillator carrying an electrically conductive moving coil, means mounted on said frame to create a magnetic field through which the moving coil passes so that a voltage is induced in said moving coil, a first and a second fixed coil mounted on said frame, a first magnetic shunt positioned next to said first coil so that changes of flux in said first shunt result in an electrical change in said first fixed coil, said first shunt also being positioned near to the path of movement of said moving coil, so that the moving coil induces flux changes in said first shunt, a source of electric current, an electric circuit having an input and an output and connected to said source, the said input being connected to said first fixed coil and responsive to electrical changes in said first fixed coil to then produce a pulse at its output, said second fixed coil being connected to said output so that upon being impulsed it creates a second magnetic field in the path of the moving coil and thereby drives said moving coil.
 2. An oscillatory system as in claim 1 wherein said means to create a magnetic field is a permaneNt magnet.
 3. An oscillatory system as in claim 1 wherein said moving coil is a single turn of conductive material.
 4. An oscillatory system as in claim 3 wherein said oscillator is a balance wheel which carries the single turn coil.
 5. An oscillatory system as in claim 1 wherein said first shunt is a U-shaped member the ends of whose arms form an air gap through which the moving coil moves.
 6. An oscillatory system as in claim 5 wherein the first fixed coil has a hole within which is positioned the shank of the first shunt.
 7. An oscillatory system as in claim 1 wherein said second coil is positioned near to a second magnetic shunt and said second magnetic shunt is positioned near the path of movement of said moving coil, to concentrate the magnetic field from said second coil.
 8. A horological instrument including an oscillator, a short circuit moving electric coil carried by said oscillator, a fixed coil positioned near the path of movement of said moving coil and adapted to induce current into the moving coil, pick-up means to detect the position of said moving coil, a current source, a circuit connected to said current source and controlled by said pick-up means, said circuit being connected to said fixed coil to provide drive pulses to said coil thereby impulsing said oscillator, and means to create a magnetic field within which the moving coil moves.
 9. A horological instrument as in claim 8 wherein said circuit is self-oscillating for self-starting of the oscillator.
 10. A horological instrument as in claim 8 wherein said circuit includes a multivibrator.
 11. A horological instrument as in claim 8 wherein said oscillator is a balance wheel and said coil is a single short-circuit turn.
 12. A horological instrument as in claim 8 wherein said pick-up means includes a magnetic shunt having an air gap through which the coil moves and a coil connected to the circuit and proximate to the shunt and wherein a permanent magnet is positioned next to the path of movement of said moving coil. 